Process for the preparation of cellulose alkyl ethers

Abstract

The present invention is related to a new process for producing cellulose C 1 -C 4 -alkyl ethers by subjecting cellulose to reaction with an alkali metal hydroxide and subjecting the resulting alkali metal salt of cellulose to reaction with an alkyl halide wherein the alkyl group contains 1 to 4 carbon atoms. The new process is characterized by subjecting 1 part by weight of cellulose to reaction with 0.5 to 4 parts by weight of the alkyl halide in a positive mixer having a fast-running mixing appliance and a container with adjustable internal pressure and cooling of the internal container wall, adding the alkali metal hydroxide in a concentrated aqueous solution or in a substantially water-free and finely divided state, and adjusting the pressure in the reaction vessel with cooling in such a way that the temperature of the reaction mixture remains in the range of from 15° to 40° C., and raising the temperature of the reaction mixture after termination of the alkalization to from 50° to 100° C.

What we claim is: 
     
       1. Process for preparing cellulose alkyl ethers by reacting cellulose with an alkali hydroxide and subsequently reacting the alkali cellulose with a C 1  -C 4  -lower alkyl halide, comprising intimately mixing the cellulose mixed with the lower alkyl halide in a quantity corresponding to from 0.5 to 4 parts by weight of lower alkyl halide to 1 part by weight of cellulose in a positive mixer having a fast-running mixing appliance and a container with adjustable internal pressure and means for cooling of the internal container wall, adding the alkali hydroxide in a concentrated aqueous solution or in a substantially water-free and finely divided state to the container, adjusting the pressure of the container with cooling in such a way that the temperature of the reaction mixture remains in the range of from 15° to 40° C., and raising the temperature to from 50° to 100° C. once alkalization is ended. 
     
     
       2. Process according to claim 1, wherein the pressure in the container is adjusted with cooling such that the temperature of the reaction mixture remains in the range of from 20° to 35° C.